ATHENS, July 14 (Reuters) - Greece said on Tuesday that it had received three bids for deep sea oil and gas drilling in the west of the country and south of the island of Crete, the latest phase of an ambitious attempt to develop untapped oil potential.

The names of the bidders will not be disclosed until tender documents are unsealed, the Energy Ministry said.

Greece, which clinched a deal with its international creditors on Monday to avoid bankruptcy, has made several fruitless attempts over the last 50 years to find big oil and gas reserves. Its debt crisis prompted the country to step up those efforts to boost revenue.

It invited investors last year to bid for test drilling in 20 offshore blocks stretching over more than 200,000 square kilometers in the Ionian Sea and south of Crete.

In March this year the new left-wing government extended the deadline for the submission of bids by two months to July 14 in an effort to attract more interest in the tender. In April it invited Chinese oil firms to bid for the tender and has also said that it expected Russian companies to show interest.

The fact that three bids were submitted was a “positive step, taking into account difficult conditions presently prevailing in the oil and gas market”, the Energy Ministry said.

“It is assessed as a positive step in the country’s attempts to utilise its subsea wealth,” it said.

The plan was code-named “Greece MegaProject” by Petroleum Geo-Services, the Oslo-based firm which conducted seismic tests.

Athens has already awarded the first drilling licences for three onshore and offshore blocks in western Greece last year to Hellenic Petroleum - in a venture with Italy’s Edison and Ireland’s Petroceltic - and the country’s sole oil producer Energean Oil & Gas, which is 45 percent owned by hedge fund Third Point.

Hellenic Petroleum and Energean were also the only two Greek firms which bid for onshore test drilling in western Greece in February. (Reporting By Angeliki Koutantou; Editing by Susan Fenton)